The Excel Autofill feature can be used to populate a range of cells with either a repeat value, or with a series of numeric values (e.g., 1, 2, 3, ...).
If you want Excel to recognise a series that is not a simple increment by 1, this can be done by typing the first two values of your series into the first and second cells of a range. Select both of these cells and again, drag the fill handle across the range to be filled. Excel will automatically recognise the pattern from the two initial cells and continue this across the selected range. Using this method, you can get Excel to fill cells by increments or decrements of any number (eg. 2, 4, 6, 8, ...).
Alternatively, if you want Excel to fill cells with repeated alternating values (eg. 1, 2, 1, 2, 1, 2, ...) you can start off the pattern in the first two (or more) cells, then, with the initial cells highlighted, drag the fill handle and then click on the 'Auto Fill Options' box. Within this box, select the option 'Copy Cells' to repeat the initial cell values across the selected range.
As dates and times are stored in Excel as numbers, these can also be used with the Excel Autofill.
By default, if you just type in a single date or time and drag the fill handle, dates and times will complete in a series, by adding one day (for dates), or one hour (for times). However, as with simple numbers, you have the option of clicking on the 'Auto Fill Options' box, to select a different type of Auto fill.
Times have the same four Auto fill options as are shown above, for simple numbers. However, for dates, there are more Auto Fill options. In addition to the four options for simple numbers, there are also the following:
The Excel Autofill will generally fill a column with text values by repeating the value(s) in the first cell(s). However, there are some text values that Excel recognises as part of a series. These are:
|Weekdays (abbreviated or full names):|
|Months (abbreviated or full names):|
|Other text containing numbers:|
The Excel Autofill feature also works with functions and formulas in Excel. However, with this type of Autofill, there is no 'series fill' option. Instead, Excel observes the rules of Absolute and Relative Cell References (ie. if a row or column reference is preceded by a $ sign, excel will keep the reference constant as the formula is copied to other cells; Otherwise, the row or column reference will be adjusted as the formula is copied to other cells.
As well as working down a column, the Autofill feature also works horizontally, across rows.
Simply drag the fill handle across the cells that you want to populate.
The Excel Autofill can happily handle data in more than one row or column. This is shown in the example below, in which cells A1 and A2 initially have numeric values 1 and 2, and cells B1 and B2 initially both have the numeric value 3.
Highlighting cells A1 to B2, and then dragging the fill handle down columns A and B causes the Autofill to complete both columns with their own series (ie. column A completes with 1, 2, 3, 4, ..., and column B completes with 3, 3, 3, 3, ...)
For speed, you can Autofill a full column by double-clicking on the fill handle of a highlighted cell (or range of cells). If the cells below or adjacent to the highlighted cell (or range) contain values, double clicking the fill handle causes the Autofill to fill down the current column until it reaches the end of the current data range.
A video on the Excel Autofill is provided on the Microsoft Office Support website.